Coordination Polymerization Of Methyl Methylacrylate By Nd(O～iPr)₃/Al(～(i)Bu)₃/CCl₄ System

Two components coordination catalysts systems, Nd(0'Pr)3/Al('Bu)3 were developed to initiate the homopolymerization of polar monomer Methyl Methacrylate (MMA). The types of solvents influence the catalysts activity dramatically. The deposit polymerization of MMA in hexane is faster than the solution polymerization of MMA in toluene. But when in the toluene medium, the growing of molecule weight of PMMA is proportional to the growing percent conversion of the polymerization of MMA.The joining of CCU as the third composition can dramatically improve the activity of the coordination catalyst system. Effects of the different conditions were studied such as: composing of the catalyst system(such as Al/Nd, III/A1 molar ratio, the rare earth elements and ligands), influence of different polymerization conditions such as, concentration of catalysts, polymerization time & temperature. The catalytic activity is affected remarkably by aging time and temperature of the catalysts. The best aging conditions was: 10-20 minutes aging under 25 "C . The best conditions for the polymerization of MMA are Al/Nd=12~16, CCVA1=0.5, 70"C, [Nd]=l X 10-2mol/L, [MMA]=5 mol/L. The microstructure of PMMA so obtained was characterized by 'H-NMR. The syndiotactic content is about 63%. The kinetics for the polymerization of MMA with Nd(0'Pr)3/Al('Bu)3/CCl4 system in toluene at 70癈 has been studied. The polymerization rate equation could be expressed as Rp = kp [Nd(O'Pr)3J [MMA]. The overall polymerization activation energy Ea measured was 74. IkJ/mol.It was the first time that the block copolymerization of methyl methacrylate (MMA) with I, 2-epoxyhexane(HO) was carried out by Nd(O'Pr)3/Al Al('Bu)3/CCl4 coordination catalysts in toluene. The influence of components of rare earth catalysts was examined. Catalytic activities of different rare earthrasystems decrease in the following order: La> Nd> Y> Tb> Er. Catalytic activities order of different organic aluminius is as: Al('Bu)3> AlH('Bu)2> AlEt3?A^EtsCb. The preferred conditions of block copolymerization are as follows: Al/Nd=16~25, CCl4/Al=0.5, 70癈. The ww of PMMA-b-P(HO) so obtained reach 1.5 X 105g/mol, and the molecular weight distribution is 3.42. The DSC results show that an PMMA block's glass temperature appears at 79.5"C, and there is also P(HO) block's small peak of melting at 63癈. The main part of PMMA block's microstructure is syndiotacticity. And the P(HO) block is chiefly make up of head-tail structures.